The MWP at the Tivoli North Bay of New York's Hudson Estuary

The MWP at the Tivoli North Bay of New York's Hudson Estuary (CO2 Science report)

The authors write that "the mid-Hudson region contains freshwater peatland archives that have not been investigated," and they therefore state that "there is a need to identify this base-line information to assess past anthropogenic activities and climatic patterns in relation to projected shifts in climate and vegetation in the Mid-Hudson Valley region," which they indicate is an important resource for over 10 million people.

What was done
Sritrairat et al. explored, as they describe it, "how climate and human impacts have influenced plant ecology, invasive species expansion, habitat loss, carbon storage, and nutrient dynamics over the past millennium based on the multiproxy analysis of sediment cores using palynology, macrofossil, sedimentological, and geochemical analyses," while working with marsh sediment cores obtained at the National Estuarine Research Reserve at Tivoli Bays on the Hudson Estuary, New York, USA.

What it means
Acknowledging that "while there is a debate if the MWP is a global phenomenon as the warming is not synchronized at all sites around the globe," Sritrairat et al. write that "many paleoclimatic records suggest widespread climatic anomalies, such as parts of Europe (Mangini et al., 2005), Tasmania (Cook et al., 1991), Asia (Yang et al., 2002), and Africa (Alin and Cohen, 2003) during the same time period." And so it is that the case for the existence of a global MWP continues to grow as demonstrated by our regular reporting of a new study that testifies of the MWP's occurrence at a new and different location.

A history of vegetation, sediment and nutrient dynamics at Tivoli North Bay, Hudson Estuary, New York (Link)


We conduct a stratigraphic paleoecological investigation at a Hudson River National Estuarine Research Reserve (HRNERR) site, Tivoli Bays, spanning the past 1100 years. Marsh sediment cores were analyzed for ecosystem changes using multiple proxies, including pollen, spores, macrofossils, charcoal, sediment bulk chemistry, and stable carbon and nitrogen isotopes. The results reveal climatic shifts such as the warm and dry Medieval Warm Period (MWP) followed by the cooler Little Ice Age (LIA), along with significant anthropogenic influence on the watershed ecosystem. A five-fold expansion of invasive species, including Typha angustifolia and Phragmites australis, is documented along with marked changes in sediment composition and nutrient input. During the last century, a ten-fold sedimentation rate increase due to land-use changes is observed. The large magnitude of shifts in vegetation, sedimentation, and nutrients during the last few centuries suggest that human activities have made the greatest impact to the marshes of the Hudson Estuary during the last millennium. Climate variability and ecosystem changes similar to those observed at other marshes in northeastern and mid-Atlantic estuaries, attest to the widespread regional signature recorded at Tivoli Bays.

Read more at CO2 Science here